They have never been more certain about what they know. Powerful new satellites can hone in on mountainous regions to measure ice melt. Stronger computers model changes in disruptive weather patterns. Scientists are even more comfortable attributing climate change to visible effects around the globe, from retreating Himalayan glaciers to southwestern U.S. droughts and acidifying oceans.

Yet scientists are still stuck in the mud trying to get that message out in Washington, where House Republicans made one of their first orders of business passing legislation to zero out research budgets for domestic and international climate efforts and unraveling a key EPA declaration that humans have played a critical role in changing the planet.

For instance, National Research Council members got a collective shrug earlier this month when they went to Capitol Hill to share their work — a congressionally mandated, 18-month review of the nuts and bolts of global warming science and ideas for what U.S. policymakers could do about it.

Only a small group of House and Senate aides showed up for private briefings on the study. And while a couple of staffers asked parochial questions about how climate change affects their districts and states, the authors also got the second degree on whether there is even a problem.

“They said, ‘There are those who believe it’s a bit of hogwash. And not only hogwash, but a fraud,’” said Albert Carnesale, chancellor emeritus at the University of California, Los Angeles and chairman of the NRC panel.

“Scientists aren’t a lobbying force,” said Andrew Revkin, author of The New York Times’s Dot Earth blog. “They’re trying to make science matter in an arena where the only way it matters is to use it to support an existing agenda.”

Carnesale said he hopes the NRC report can help prod U.S. lawmakers to curb emissions and prepare for changes that are already being locked in. But he acknowledged the challenge is to get policymakers to at least accept there are risks associated with doing nothing.

“For people for whom this is a matter of ideology or faith, there’s no argument that’s going to convince them,” he said.

Princeton University mechanical engineering professor Robert Socolow said climate scientists are disadvantaged because they’re trying to engage the public with an issue that essentially sounds like a bummer.

“If you give people a message they don’t want to hear, they’ll push it away,” he said.

Still, he argued that the climate issue shouldn’t be sugarcoated. “This is the kind of thing that’s going on,” he said. “I think if we could say more of that and engage people and say, ‘This is lousy news, boys and girls. This isn’t what we’d like to be telling. But this is what the science is saying. We have an obligation together to come to grips with it.’”

The NRC report — which pulled together experts from engineering, science, business, nonprofits, government and politics — had as its key conclusion, “Climate change is occurring, is very likely caused by human activities and poses significant risks for a broad range of human and natural systems.”

Of 1,100 references in the report, half came from new studies released since the last major U.N. Intergovernmental Panel on Climate Change report published in 2007.

And more groundbreaking climate science reports are also coming out.

Using lake sediments, tree rings and ice cores, scientists earlier this month reported that the Arctic’s summer temperatures over the past few decades have been higher than any time in the past 2,000 years.

In the same report, scientists also said that mountain glaciers, ice caps and the Greenland ice sheet are declining faster since 2000 than in the previous decade, which may lead to a global sea level rise of between 2.95 and 5.25 feet by 2100. That’s substantially higher than the 7-to-23-inch rise projected in the 2007 IPCC report, which had excluded data about Greenland because none were available by a key cutoff date.

“It’s been challenging in our political system to take the kinds of actions that we know are dictated by the science and by what we see in front of our eyes,” Secretary of State Hillary Clinton said during a visit this month to Greenland, where Arctic nations worked on preparations for an ice-free North Pole within a matter of decades.

Part of the problem is a lull in public concern about climate change and acceptance of the science. Pollsters attribute it in part to the controversy over the more than 1,000 emails stolen in 2009 from the Climate Research Unit at the University of East Anglia in Britain.

Dubbed Climategate, global warming skeptics argued the materials are proof of collusion among top climate scientists to keep out dissenting views — although the researchers have since been exonerated by several internal investigations.

The IPCC also undermined its cause when it included bad information in its Nobel Prize-winning 2007 report about the date that Himalayan glaciers are likely to melt.

Republican presidential candidates are backtracking on climate science three years after their last nominee, John McCain, championed a cap-and-trade system to curb emissions.

The GOP-led House is also skeptical. It included a rider in the fiscal 2011 spending bill that defunded a new National Oceanic and Atmospheric Administration climate office and also tried halting the U.S. contributions to the IPCC.

The House also passed legislation that would overturn the EPA’s endangerment finding that greenhouse gases threaten public health and the environment, the key scientific precursor allowing the agency to do its regulations.

“The evidence we have suggests the whole thing has been a hoax and a fraud and yet the left marches on,” Rush Limbaugh said last week on his radio show.

As for the IPCC, authors have launched their next series of reports on the latest climate science too. A special study on extreme weather events, disasters and adaptation is coming in late 2011; a final synthesis report is due in September 2014.

Responding to the Himalayan glacier flap, the IPCC this month adopted new management and communication protocols, including how to address alternative views and setting up practices for dealing with scientific uncertainty and mistakes.

“We need to equip ourselves with the ability and capacity to deal with the heightened scrutiny … which we have been subjected to recently,” IPCC Chairman Rajendra Pachauri said earlier this month during a conference in Abu Dhabi.